This is an excellent point! Thank you for making it 
When you import text (for a new lesson), the LingQ importer splits sentences based on punctuation: . (period) ? (question mark), etc.
Punctuation that is usually seen at the end of sentences (at least for the English Language).
An Example:
So often, when I import Korean text like:
LingQ will split the sentence into two sentences like this:
그러다 올초 해외 출판사들과 미팅을 갖는데 이렇게 얘기하더라고요.
“우리나라는 일요일에 책을 출간하지 않는다.”
Rather than keeping the text together in examples like these, LingQ reads the periods " . " in the sentence and splits it into two sentences.
A member of LingQ support also advised to insert end-of-sentence markers (i.e., punctuation) for importing text.
Edit: So modifying the sentence markers would look something like this (for the above example):
Changing the period to a colon:
그러다 올초 해외 출판사들과 미팅을 갖는데 이렇게 얘기하더라고요: “우리나라는 일요일에 책을 출간하지 않는다.”
Or
Changing the period to a comma:
그러다 올초 해외 출판사들과 미팅을 갖는데 이렇게 얘기하더라고요, “우리나라는 일요일에 책을 출간하지 않는다.”
So the LingQ keeps the text together as one “complete thought.”
But I’ve avoided doing that to focus on reading Korean the way Koreans use it.
I just take the extra time manually combining those sentences that LingQ splits when importing them so far.
Because of your excellent point above, I’m inclined to continue avoiding modifications of the end-of-sentence markers (punctuation).
I hope this makes more sense! Sorry for the initial confusion @TerraEarth 